The following warnings occurred:
Warning [2] Undefined array key 70513 - Line: 275 - File: inc/plugins/threaded_mode.php PHP 8.1.2-1ubuntu2.14 (Linux)
File Line Function
/inc/class_error.php 153 errorHandler->error
/inc/plugins/threaded_mode.php 275 errorHandler->error_callback
/inc/plugins/threaded_mode.php 23 ThreadedMode::showthread_threaded
/inc/class_plugins.php 142 threaded_mode_showthread_threaded
/showthread.php 918 pluginSystem->run_hooks
Warning [2] Undefined array key 70515 - Line: 275 - File: inc/plugins/threaded_mode.php PHP 8.1.2-1ubuntu2.14 (Linux)
File Line Function
/inc/class_error.php 153 errorHandler->error
/inc/plugins/threaded_mode.php 275 errorHandler->error_callback
/inc/plugins/threaded_mode.php 23 ThreadedMode::showthread_threaded
/inc/class_plugins.php 142 threaded_mode_showthread_threaded
/showthread.php 918 pluginSystem->run_hooks
Warning [2] Undefined array key 70516 - Line: 275 - File: inc/plugins/threaded_mode.php PHP 8.1.2-1ubuntu2.14 (Linux)
File Line Function
/inc/class_error.php 153 errorHandler->error
/inc/plugins/threaded_mode.php 275 errorHandler->error_callback
/inc/plugins/threaded_mode.php 23 ThreadedMode::showthread_threaded
/inc/class_plugins.php 142 threaded_mode_showthread_threaded
/showthread.php 918 pluginSystem->run_hooks
Warning [2] Undefined array key 70517 - Line: 275 - File: inc/plugins/threaded_mode.php PHP 8.1.2-1ubuntu2.14 (Linux)
File Line Function
/inc/class_error.php 153 errorHandler->error
/inc/plugins/threaded_mode.php 275 errorHandler->error_callback
/inc/plugins/threaded_mode.php 23 ThreadedMode::showthread_threaded
/inc/class_plugins.php 142 threaded_mode_showthread_threaded
/showthread.php 918 pluginSystem->run_hooks
Warning [2] Undefined array key 70597 - Line: 275 - File: inc/plugins/threaded_mode.php PHP 8.1.2-1ubuntu2.14 (Linux)
File Line Function
/inc/class_error.php 153 errorHandler->error
/inc/plugins/threaded_mode.php 275 errorHandler->error_callback
/inc/plugins/threaded_mode.php 23 ThreadedMode::showthread_threaded
/inc/class_plugins.php 142 threaded_mode_showthread_threaded
/showthread.php 918 pluginSystem->run_hooks
Warning [2] Undefined variable $thread - Line: 295 - File: inc/plugins/threaded_mode.php PHP 8.1.2-1ubuntu2.14 (Linux)
File Line Function
/inc/class_error.php 153 errorHandler->error
/inc/plugins/threaded_mode.php 295 errorHandler->error_callback
/inc/plugins/threaded_mode.php 23 ThreadedMode::showthread_threaded
/inc/class_plugins.php 142 threaded_mode_showthread_threaded
/showthread.php 918 pluginSystem->run_hooks
Warning [2] Trying to access array offset on value of type null - Line: 295 - File: inc/plugins/threaded_mode.php PHP 8.1.2-1ubuntu2.14 (Linux)
File Line Function
/inc/class_error.php 153 errorHandler->error
/inc/plugins/threaded_mode.php 295 errorHandler->error_callback
/inc/plugins/threaded_mode.php 23 ThreadedMode::showthread_threaded
/inc/class_plugins.php 142 threaded_mode_showthread_threaded
/showthread.php 918 pluginSystem->run_hooks
Warning [2] Undefined variable $fid - Line: 295 - File: inc/plugins/threaded_mode.php PHP 8.1.2-1ubuntu2.14 (Linux)
File Line Function
/inc/class_error.php 153 errorHandler->error
/inc/plugins/threaded_mode.php 295 errorHandler->error_callback
/inc/plugins/threaded_mode.php 23 ThreadedMode::showthread_threaded
/inc/class_plugins.php 142 threaded_mode_showthread_threaded
/showthread.php 918 pluginSystem->run_hooks
Warning [2] Undefined array key 70516 - Line: 331 - File: inc/plugins/threaded_mode.php PHP 8.1.2-1ubuntu2.14 (Linux)
File Line Function
/inc/class_error.php 153 errorHandler->error
/inc/plugins/threaded_mode.php 331 errorHandler->error_callback
/inc/plugins/threaded_mode.php 332 ThreadedMode::buildtree
/inc/plugins/threaded_mode.php 332 ThreadedMode::buildtree
/inc/plugins/threaded_mode.php 304 ThreadedMode::buildtree
/inc/plugins/threaded_mode.php 23 ThreadedMode::showthread_threaded
/inc/class_plugins.php 142 threaded_mode_showthread_threaded
/showthread.php 918 pluginSystem->run_hooks
Warning [2] Undefined array key 70517 - Line: 331 - File: inc/plugins/threaded_mode.php PHP 8.1.2-1ubuntu2.14 (Linux)
File Line Function
/inc/class_error.php 153 errorHandler->error
/inc/plugins/threaded_mode.php 331 errorHandler->error_callback
/inc/plugins/threaded_mode.php 332 ThreadedMode::buildtree
/inc/plugins/threaded_mode.php 332 ThreadedMode::buildtree
/inc/plugins/threaded_mode.php 304 ThreadedMode::buildtree
/inc/plugins/threaded_mode.php 23 ThreadedMode::showthread_threaded
/inc/class_plugins.php 142 threaded_mode_showthread_threaded
/showthread.php 918 pluginSystem->run_hooks
Warning [2] Undefined array key 70597 - Line: 331 - File: inc/plugins/threaded_mode.php PHP 8.1.2-1ubuntu2.14 (Linux)
File Line Function
/inc/class_error.php 153 errorHandler->error
/inc/plugins/threaded_mode.php 331 errorHandler->error_callback
/inc/plugins/threaded_mode.php 332 ThreadedMode::buildtree
/inc/plugins/threaded_mode.php 304 ThreadedMode::buildtree
/inc/plugins/threaded_mode.php 23 ThreadedMode::showthread_threaded
/inc/class_plugins.php 142 threaded_mode_showthread_threaded
/showthread.php 918 pluginSystem->run_hooks
Warning [2] Undefined variable $theme - Line: 3 - File: inc/plugins/threaded_mode.php(305) : eval()'d code PHP 8.1.2-1ubuntu2.14 (Linux)
File Line Function
/inc/class_error.php 153 errorHandler->error
/inc/plugins/threaded_mode.php(305) : eval()'d code 3 errorHandler->error_callback
/inc/plugins/threaded_mode.php 305 eval
/inc/plugins/threaded_mode.php 23 ThreadedMode::showthread_threaded
/inc/class_plugins.php 142 threaded_mode_showthread_threaded
/showthread.php 918 pluginSystem->run_hooks
Warning [2] Trying to access array offset on value of type null - Line: 3 - File: inc/plugins/threaded_mode.php(305) : eval()'d code PHP 8.1.2-1ubuntu2.14 (Linux)
File Line Function
/inc/class_error.php 153 errorHandler->error
/inc/plugins/threaded_mode.php(305) : eval()'d code 3 errorHandler->error_callback
/inc/plugins/threaded_mode.php 305 eval
/inc/plugins/threaded_mode.php 23 ThreadedMode::showthread_threaded
/inc/class_plugins.php 142 threaded_mode_showthread_threaded
/showthread.php 918 pluginSystem->run_hooks
Warning [2] Undefined variable $theme - Line: 3 - File: inc/plugins/threaded_mode.php(305) : eval()'d code PHP 8.1.2-1ubuntu2.14 (Linux)
File Line Function
/inc/class_error.php 153 errorHandler->error
/inc/plugins/threaded_mode.php(305) : eval()'d code 3 errorHandler->error_callback
/inc/plugins/threaded_mode.php 305 eval
/inc/plugins/threaded_mode.php 23 ThreadedMode::showthread_threaded
/inc/class_plugins.php 142 threaded_mode_showthread_threaded
/showthread.php 918 pluginSystem->run_hooks
Warning [2] Trying to access array offset on value of type null - Line: 3 - File: inc/plugins/threaded_mode.php(305) : eval()'d code PHP 8.1.2-1ubuntu2.14 (Linux)
File Line Function
/inc/class_error.php 153 errorHandler->error
/inc/plugins/threaded_mode.php(305) : eval()'d code 3 errorHandler->error_callback
/inc/plugins/threaded_mode.php 305 eval
/inc/plugins/threaded_mode.php 23 ThreadedMode::showthread_threaded
/inc/class_plugins.php 142 threaded_mode_showthread_threaded
/showthread.php 918 pluginSystem->run_hooks
Warning [2] Undefined variable $lang - Line: 5 - File: inc/plugins/threaded_mode.php(305) : eval()'d code PHP 8.1.2-1ubuntu2.14 (Linux)
File Line Function
/inc/class_error.php 153 errorHandler->error
/inc/plugins/threaded_mode.php(305) : eval()'d code 5 errorHandler->error_callback
/inc/plugins/threaded_mode.php 305 eval
/inc/plugins/threaded_mode.php 23 ThreadedMode::showthread_threaded
/inc/class_plugins.php 142 threaded_mode_showthread_threaded
/showthread.php 918 pluginSystem->run_hooks
Warning [2] Attempt to read property "messages_in_thread" on null - Line: 5 - File: inc/plugins/threaded_mode.php(305) : eval()'d code PHP 8.1.2-1ubuntu2.14 (Linux)
File Line Function
/inc/class_error.php 153 errorHandler->error
/inc/plugins/threaded_mode.php(305) : eval()'d code 5 errorHandler->error_callback
/inc/plugins/threaded_mode.php 305 eval
/inc/plugins/threaded_mode.php 23 ThreadedMode::showthread_threaded
/inc/class_plugins.php 142 threaded_mode_showthread_threaded
/showthread.php 918 pluginSystem->run_hooks





Unexpected Rounding



#3

I am doing some FV & PV calculations on my 12c and encountering some rounding errors.

example-
calc # of periods need to compound to reach FV.

1000 invested at 8% compounded annually to reach 3670 should equal 16.89 periods, my 12c says 17 periods

1000 invested at 8% compounded semi annually to reach 3670 should equal 33.15/2=16.58 periods, my 12c says 34/2=17 periods

Have I a setting to change?


#4

OK - Unfortunately I'm not yet proficient enough with my own 'new' HP12C so I can't check your findings but I'll be the first to ask the obvious anyway - how many decimal places are shown in your result?

(I assume you have pressed [f] [2] to display 2 decimal places).

Hope this helps.

Mike T.


#5

Mike-
Thanks for replying. I am showing 2 or greater decimal places when this happens.

#6

except for a few cases.

Examples:

If the true calculated n is 18.6, it rounds up to 19.

If the true calculated n is 18.1, it rounds up to 19.

If the true calculated n is 18.0002, it rounds down to 18.

Been that way since the 12c's release back in 1981. It is described in the 12c owners manual (and the 12c platinum owners manual is available free at www.hp.com/calculators. It works for the original 12c in almost all respects.

Gene

#7

Hello,

Quote:
1000 invested at 8% compounded annually to reach 3670 should
equal 16.89 periods, my 12c says 17 periods

You'll get the 16.89 on the HP-38C, which was the HP Financial
Calculator(HPFC) just prior to the 12C, and also on the
HP-18C, which was the HPFC that followed the 12C.

I just found my old program for the 12C which makes it also
give the 16.89. I call it the "pulveriser" as it takes i and
PMT and creates tiny but equivalent replicas of them :-).

Here is the pulveriser, in 15 lines:

1 [n] [STO][PV] [FV] [X<>Y] 0 [PMT] [FV] [RDN] [n] [i]
[RDN] [FV] [PMT] [g][GTO]00

For your case where PMT=0 the above could be simplified of
course, or you could just calculate n as LN(3.67)/LN(1.08).

Or, try this, where [R/S] runs the pulveriser:

8 [i] 0 [PMT]

[EEX] 9 [R/S]

1000 [CHS] [PV] 3670 [FV] [n]

[EEX] 9 [/] ->16.89215375

This method also works for calculating n for non-zero PMT.

Ironically the method used in the pulveriser above does *not*
work at all well on the HP-38C or the HP-18C (or in fact any
other HP TVM implementation). One could argue that it
is not of course needed on those machines, but it is also
useful for finding equivalent effective rates of interest and
PMT in real life - with a factor if 12 or 52 for example.

Anyway, while I too found the n-solving on the 12C unexpected,
I am at least pleased to report that the 12C represented a
peak in HP financial mathematics knowledge/implementation. For
example, look at what you get for i when trying this on HP TVM
programs:

[EEX] 9 [n] 1 [PV] 0 [PMT] 1.05 [CHS] [FV] [i] [RCL][n] [*]

On the 12C we get:4.879016417 (exactly 100*LN(1.05))

On the 38C we get:4.800000000

On the 18C we get:4.87900000000

On the 49G we get: the same as the 18C

On the 200LX :4.8790164000000

It appears that when HP re-did their TVM application for the
18C, they went back to the 38C microcode. Our 12C stands
alone! It has an aura of reliability, not without reason, and it shows in delightfully unexpected ways.

Cheers,
Tony


Possibly Related Threads…
Thread Author Replies Views Last Post
  HP Prime program: rounding to a fraction Patrice 3 1,661 10-31-2013, 06:16 AM
Last Post: Joe Horn
  HP Prime: Rounding error in determinant Stephan Matthys 3 1,607 10-25-2013, 09:29 PM
Last Post: Walter B
  Unexpected problem with the real Prime Javier Goizueta 4 1,903 10-08-2013, 01:00 PM
Last Post: Marcus von Cube, Germany
  Rounding of 10^x Olivier De Smet 8 2,499 08-28-2013, 06:33 AM
Last Post: Dieter
  Estimating Accumulated Rounding Errors Egan Ford 13 3,196 08-16-2012, 01:49 PM
Last Post: Egan Ford
  WP34s: number display and rounding Dieter 4 1,410 10-14-2011, 05:11 PM
Last Post: Marcus von Cube, Germany
  rounding, from another posting, a question... Geoff Quickfall 6 1,924 08-13-2011, 06:08 AM
Last Post: Paul Dale
  Rounding errors BruceH 4 1,642 11-22-2009, 11:24 AM
Last Post: Vieira, Luiz C. (Brazil)
  Rounding Revisited Rodger Rosenbaum 5 1,703 07-22-2009, 02:29 PM
Last Post: Rodger Rosenbaum
  Rounding conventions Wayne Best 38 7,980 07-05-2009, 04:39 AM
Last Post: Rodger Rosenbaum

Forum Jump: